The Present Disclosure relates, generally, to waveguides, and, more particularly, to waveguides in which the surfaces of a dielectric corresponding to the long sides of a rectangular transverse section bulge outward and the dielectric closely adheres to the outer conductor.
Waveguides have been proposed for transmitting high-frequency waves, such as millimeter waves and microwaves. An example is disclosed in Japanese Patent Application No. [8-195605], the content of which is incorporated in its entirety herein.
FIG. 9 is a perspective view of a conventional waveguide. In this figure, 851 is a dielectric rod made of a flexible polymer and having an oval-shaped cross-section. Also, 861 is metal tape wound around the surface of the dielectric rod 851. This tape is made of thin copper foil with a low resistance. High-frequency waves are guided through the dielectric rod 851 sealed inside.
However, the dielectric rod 851 inside conventional waveguides cannot have a square cross-sectional profile because metal tape 861 is wound around its surface. Therefore, a waveguide with a conventional square cross-sectional profile cannot be provided as a waveguide for microwaves and millimeter waves. Even if metal tape 861 were wound tightly around a dielectric rod 851 with a rectangular cross-sectional profile, small gaps would occur between the tape and the surface of the dielectric rod 851 on the tong sides of the rectangle. When there are gaps between the surface of the dielectric rod 851 and the metal tape 861, transmission loss becomes unstable, and electromagnetic waves in the higher frequency bands cannot be stably transmitted.